Colorants known as dyes or pigments are widely used as fiber dying materials, resin and paint coloring materials, image forming materials in photography, printing, copiers, and printers, as well as light absorbing materials in color filters. In recent years, proposed have been various hard copy image forming dyes employed for ink-jet printing, electrophotography, silver salt photography, and thermal transfer applications. Further, along with the progress of electronic imaging, increased has the demand for filter dyes for solid state image pick-up tubes and color liquid crystal display, as well as dyes for optical recording media utilizing semiconductor lasers, whereby dye application fields have been widened. The common qualities required for the above dyes are listed below.
Namely, listed are preferable hues for color reproduction, optimal spectral absorption characteristics, sufficient image resistance to such as light, heat, moisture, and chemicals, as well as sufficiently high molar absorption coefficients.
Heretofore, azomethine dyes have been employed as an image forming dye for silver halide photosensitive color photographic materials utilizing the subtractive color process based on the three-color mixture of yellow, magenta, and cyan. These dyes are disclosed and proposed as color hard copy image forming dyes (refer, for example, to Patent Documents 1–6). However, desired image durability of these dyes has not yet been achieved. Further, metal complex dyes exhibiting good lightfastness are described (refer, for example, to Patent Documents 7–9). However, they are disadvantageous for the use as image forming dyes due to low molar absorption coefficient as well as specific absorption wavelengths. Subsequently, it is still desired to develop dyes providing the aforesaid qualities.
In color copiers and color laser printers utilizing electrophotographic systems, commonly employed are toners in which colorants are dispersed into resinous particles, or colorants are adsorbed onto the surface of resinous particles. Listed as performance characteristics demanded for color toners are absorption capable of realizing preferable color reproduction regions, especially high light transmittance (transparency) when used in overhead projectors (hereinafter referred to as OHP) and various kinds of durability under ambient conditions during use.
Japanese Patent Publication Open to Public Inspection (hereinafter referred to as JP-A) Nos. 62-157051 and 6-118715 disclose toners in which pigments as a colorant are dispersed into particles. The resulting toners exhibit the desired lightfastness. However, since they tend to coagulate due to insolubility, a decrease in transparency and hue variation of transmitted light become a problem. On the other hand, each of JP-A Nos. 2-207274, 2-207273, 3-276161, 7-209912, 8-123085, and 2002-371214 discloses toners in which dyes are employed as a colorant. The resulting toners exhibit high transparency and no variation of color hue, but insufficient lightfastness.
The following characteristics are demanded for dyes employed for ink-jet recording inks: Highly soluble in solvents, possibility of high density recording, preferable color hues, high durability against light, heat, air, water and chemicals, desired fixability and minimal penetration onto image receiving materials, high storage stability in the form of ink, no toxicity, and high purity, as well as lower cost. However, it is very difficult to find dyes which satisfy these demands at the desired high level. Specifically, increasingly demanded are dyes which exhibit desired hues and excellent lightfastness.
JP-A Nos. 61-36362 and 2-212566 disclose ink-jet recording inks which are aimed at the compatibility of color hues and lightfastness. However, in cases in which dyes employed in each patent are employed as a water-soluble ink, solubility in water is insufficient.                (Patent Document 1) pages 7–9 of JP-A No. 59-184339        (Patent Document 2) pages 10–13 of JP-A No. 63-145281        (Patent Document 3) pages 3–4 of JP-A No. 2-3450        (Patent Document 4) JP-A No. 4-359968        (Patent Document 5) JP-A No. 7-166084        (Patent Document 6) JP-A No. 10-264541        (Patent Document 7) JP-A No. 2-76884        (Patent Document 8) JP-A No. 9-131973        (Patent Document 9) JP-A No. 9-143382        